I think I fixed my Sigma 50mm Focus issue!

Hi guys and gals!,

thought some of you might be interested in this....

I recently came across a post by gravy graffix (see post 20) where he discussed removing the shims....Well, I tried it and it seems to work.

A little explanation....my Sigma 50mm always front focused at long distances but not at short, if I adjusted it via MA it would fix the long distance, but cause issues at shorter distances, so basicaly up till now Iv just put up with it.

So today I thought Id have a go at removing some shims...I ended up removing both (!) and it now front focuses at both the short range and long range....while this may sound bad its infact fantastic! Iv now used MA +15 and it now consistently focuses at both long and short distances!

Looking forward to some tests.

Very cool

What are you considering long distances? Thanks

I Think i would send it back and buy a canon

umphotography wrote in post #13985189
I Think i would send it back and buy a canon

The alternative, the Canon, is probably one of Canon's most unreliable lenses especially in the AF department. It would be great if Canon offered a genuine alternative of similar standard to their 28 F/1.8 and 85 F/1.8, but unfortunately they do not.

I was under the impression the equivalent lens would be the Canon 50 1.4 which has decent autofocus and is cheaper than the Sigma equivalent unlike the 1.8 you're describing.

flowrider wrote in post #13985753
I was under the impression the equivalent lens would be the Canon 50 1.4 which has decent autofocus and is cheaper than the Sigma equivalent unlike the 1.8 you're describing.

I'm pretty sure phreeky is talking about the Canon 50 1.4. In my experience, unreliable is putting it mildly.

ljason8eg wrote in post #13985797
I'm pretty sure phreeky is talking about the Canon 50 1.4. In my experience, unreliable is putting it mildly.

Yep, the 50 F/1.4 is what I was talking about. It is a fragile lens that is a step below the other FLs I listed (28mm and 85mm) and could do with an upgrade to their standard, but unfortunately I can see Canon skipping that and going straight for a super expensive IS version.

I used to own the canon 50mm 1.4 and I was not a fan.... Plasticky build, clicky motor that would somtimes just stop working, and strange ghosting at f1.4...

That said, it focused better than the sigma,but that's the best I can say about it.

Even with the Sigmas random AF issues I still would choose it over the canon version.... Not the L though.....if only I had the money!


Iv done some more testing...and it's still focusing well. I would say at f1.4 80% of test shots I could not ask for better accuracy. The other 20% are slight miss focuses or user error. But, I am yet to try some any long distance shots.... It could be the lens fails miserably at that distance now with the shims removed!

update - Im sorry to say removing the shims has not worked - nether has removing just the one of the two..

While removing them alowed me to nail focus inside the house (and upto around 20 meter distance), when focusing on the horizon the focus was wildly out...every single time.

I'm sorry to respond to an old thread.
I recently picked up this lens from an ebay auction for just $220, but it is front focusing. Anyway, I still use it as a portrait manual focus lens, and it gives acceptably sharp images wide open, and nice and smooth bokeh, so I like it.
As I use this lens just for portraits and the objects will never be as far as 20 meter or longer, I think I will try this mod.
Thank you for sharing.

I have owned 4 of the Sigma 50 1.4 int he past. and my current one was giving me issues it was all over and very inconsistent.
I sent it to sigma and they did whatever to it and it came back being able to MA it and it is very consistent in focusing now. the only time I have issues is at 1.4 at the min focus distance. it seems to front focus just a little bit

I would really like to send mine to Sigma, but the country where I live does not have Sigma service center, and it would be very expensive to send it to USA. I'm afraid I'm on my own here. I will try to remove the rings as soon as I get a thin screwdriver.